891727 Mercruiser PISTON, With Rings and Pin

Illustration 1 g00851009
Typical example
Grounding Stud To Battery Ground ("-")
Illustration 2 g00851013
Typical example
Alternate Grounding Stud To Battery Ground ("-")
The engine must have a wire ground to the battery. Ground wires or ground straps should be combined at ground studs that are only for ground use. All of the grounds should be tight and free of corrosion.All of the ground paths must be capable of carrying any likely current faults. An AWG #0 or larger wire is recommended for the grounding strap to the cylinder head.The engine alternator should be battery ground with a wire size that is capable of managing the full charging current of the alternator.
When boost starting an engine, the instructions in Systems Operation, "Engine Starting" should be followed in order to properly start the engine.This engine may be equipped with a 12 volt starting system or a 24 volt starting system. Only equal voltage for boost starting should be used. The use of a higher voltage will damage the electrical system.The Electronic Control Module (ECM) must be disconnected at the "J1/P1" and "J2/P2" locations before welding on the vehicle.
The engine has several input components which are electronic. These components require an operating voltage. Unlike many electronic systems of the past, this engine is tolerant to common external sources of electrical noise. Buzzers that use electrical energy can cause disruptions in the power supply. If buzzers are used anywhere on the machine, the engine electronics should be powered directly from the battery system through a dedicated relay. The engine electronics should not be powered through a common power bus with other devices that are powered by the key start switch.Engine Electrical System
The electrical system has the following separate circuits:
Charging
Starting (If equipped)
Low amperage accessoriesSome of the electrical system components are used in more than one circuit. The following components are common in more than one circuit:
Battery or batteries
Circuit breakers
Battery cables
AmmeterThe charging circuit is in operation when the engine is running. An alternator makes electricity for the charging circuit. A voltage regulator in the circuit controls the electrical output in order to keep the battery at full charge.The starting circuit is activated only when the start switch is activated.The low amperage accessory circuit and the charging circuit are connected through the ammeter. The starting circuit is not connected through the ammeter.Charging System Components
Alternator
The alternator is driven by a belt from the crankshaft pulley. This alternator is a three-phase, self-rectifying charging unit, and the regulator is part of the alternator. The alternator design has no need for slip rings and the only part that has movement is the rotor assembly. All conductors that carry current are stationary. The following conductors are in the circuit:
Field winding
Stator windings
Six rectifying diodes
Regulator circuit componentsThe rotor assembly has many magnetic poles that look like fingers with air space between each of the opposite poles. The poles have residual magnetism. The residual magnetism produces a small magnetic field between the poles. As the rotor assembly begins to turn between the field winding and the stator windings, a small amount of alternating current (AC) is produced. The AC current is produced in the stator windings from the small magnetic field. The AC current is changed to direct current (DC) when the AC current passes through the diodes of the rectifier bridge. The current is used for the following applications:
Charging the battery
Supplying the low amperage accessory circuit
Strengthening the magnetic fieldThe first two applications use the majority of the current. As the DC current increases through the field windings, the strength of the magnetic field is increased. As the magnetic field becomes stronger, more AC current is produced in the stator windings. The increased speed of the rotor assembly also increases the current and voltage output of the alternator. The voltage regulator is a solid-state electronic switch. The voltage regulator senses the voltage in the system. The voltage regulator switches ON and OFF many times per second in order to control the field current for the alternator. The alternator uses the field current in order to generate the required voltage output.
Never operate the alternator without the battery in the circuit. Making or breaking an alternator connection with heavy load on the circuit can cause damage to the regulator.
Illustration 3 g01124525
Typical alternator components
(1) Regulator
(2) Roller bearing
(3) Stator winding
(4) Ball bearing
(5) Rectifier bridge
(6) Field winding
(7) Rotor assembly
(8) Fan Starting System Components
Starting Solenoid
Illustration 4 g00317613
Typical starting solenoid
Illustration 5 g01799270
Typical starting motor components
(9) Field
(10) Solenoid
(11) Clutch
(12) Pinion
(13) Commutator
(14) Brush assembly
(15) Armature The